Structure with underwater foundation



Sept. 18, 1962 L. MULLER STRUCTURE WITH UNDERWATER FOUNDATION 4 Sheets-Sheet 1 Filed April 5, 1960 Sept. 18, 1962 MULLER STRUCTURE WITH UNDERWATER FOUNDATION Filed April 5, 1960 4 Sheets-Sheet 2 jm eyrzo/r LUDW/G MULLER M N M A 7' TOE/VEKS Sept. 18, 1962 L. MULLER STRUCTURE WITH UNDERWATER FOUNDATION Filed April 5, 1960 4 Sheets-Sheet 3 Ha -M NW A -r TDRIVEYS Sept. 18, 1962 L. MULLER STRUCTURE WITH UNDERWATER FOUNDATION 4 Sheets-Sheet 4 Filed April 5, 1960 jm gnforz' LUDW G MULL El? AT EA/EYS United States Patent 3,054,268 STRUCTURE WITH UNDERWATER FOUNDATION Ludwig Miiller, Heinrich-Heine-Strasse 41, Mai-burg (Lahn), Germany Filed Apr. 5, 1960, Ser. No. 20,148 Claims priority, application Germany Apr. 6, 1959 4 Claims. (Cl. 61-52) The .present invention relates to a method of grounding an underwater foundation, and more particularly to a method of grounding such foundation by using a floating caisson. The invention also relates to a structure for carrying out the method of the invention.

In order to ground the foundations for heavy building structures in deep, stagnant or flowing water, for instance, the foundations for bridge towers or piles in rivers, the foundations for lighthouses and pier heads along the coast, etc., it is known to use floating caissons made of steel or steel reinforced concrete. The caissons are prefabricated over water by means of dry docks, floating docks, pontoons, etc. They are then caused to float freely in sufliciently deep water and towed to the location at which they are to be grounded. At the selected location the floating caissons are settled on the ground by flooding the caissons. The flooded caissons will penetrate due to their own weight more or less deeply into the bottom of the water, depending upon the bottom strata in question. Thereupon the caissons which initially rest upon the bottom, are gradually lowered by means of any one of the suitable and known methods of grounding by means of pressure air until solid strata are reached capable of supporting the load. The pressure air serves gradually to flush out the ground below the caisson.

This method of grounding of floating caissons by means of pressure air is generally very expensive and time consuming. It is also quite dangerous for the work crew, especially if load-supporting ground is reached only considerably below the bottom of the water. Such conditions are frequently encountered along the coasts of the sea and in the estuaries of large rivers where it is often necessary to lower the flooding caissons eighty feet and more below the bottom of the water. Furthermore, the need for deep grounding of the often very large caissons which is inherent in the pressure air method, entails the use of large quantities of concrete for build-up of the foundation whereby the construction of foundations by the methods as heretofore known is further increased in costs.

It is a broad object of the invention to provide a novel and improved method of constructing a safe footing or foundation for building structures in the ground below a body of Water which eliminates the heretofore required deep lowering of the foundations, even where the bottom strata are unfavorable for erection of a heavy structure.

Another object of the invention is to provide a novel and improved method of constructing a strong foundation at much lower costs and in shorter time than was heretofore possible under similar conditions, especially in deep water.

Still another object of the invention is to provide a novel and improved method of constructing a foundation which affords the advantage of an extremely high loadcarrying capacity and resistance to capsizing.

It is also an object of the invention to provide novel and improving structural means for carrying out the method of the invention.

Generally, the structural means of the invention reside in providing a caisson which can be flooded and which has through its walls apertures oriented downwardly, and in further providing piles which extend through the aper- "ice tures of a flooded caisson resting upon the bottom of the water by its own weight and which can be deeply driven into solid ground below the caisson. The driven piles are then anchored in and keyed to the ground by means of concrete jackets encasing the piles and formed by filling a cavity dug about the piles during the driving operation by means of an enlarged pile foot and closed by a collar at the upper end of the cavity.

Other and further objects, features and advantages of the invention will be pointed out hereinafter and setforth in the appended claims forming part of the application.

In the accompanying drawing a preferred embodiment of the invention is shown by way of illustration and not by way of limitation.

In the drawing:

FIG. 1 is an elevational sectional view of aground structure according to the invention, the caisson being shown floating in the water above the location at which the foundation is to be constructed.

FIG. 2 is a view similar to FIG. 1 and showing the caisson settled on the ground after flooding.

FIG. 2a is a sectional enlarged view of a detail of FIG. 2.

FIG. 3 is a view similar to FIG. 2 and showing the piles driven into the ground below the settled caisson.

FIG. 4 is a section taken on line 44 of FIG. 2, and

FIG. 5 is a sectional fragmentary view of a caisson and a pile fitted therein on an enlarged scale.

Referring now to the figures in detail, the exemplifica tion of the invention as shown in the figures, comprises a caisson made of concrete and having an approximately frusto-conical configuration. A number of preferably circumferentially spaced, longitudinal bores extend through the side walls of the caisson and similar bores 8 are provided in a boss 1a rising from the bottom wall of the caisson. As is evident, all the bores are oriented downwardly and the lower portion of each bore is widened to form a shoulder 9. A pile 2 comprising a hollow pile shaft and a hollow enlarged foot 3 extends through each of the bores 7 and '8. A sealing collar formed by two superimposed ring members 5 and 6 secured to each other by anchor bolts 20, as can best be seen in FIG. 5, is fitted in the widened portion of each bore to abut against the respective shoulder 9. A single piece collar instead of the shown split collar may also be used. The pile shafts are slidable within the collars with the pile head 3 protruding downwardly from the collar. In order to strengthen the seal between collar and the pile shaft a central sealing bushing 11 is preferably provided. The collar assembly further includes a sealing sleeve 4 encompassing collar parts 5 and 6 and extending toward the tip of the pile foot 3 as shown in FIG. 5.

Assuming now that a caisson with piles inserted therein has been floated into the position of FIG. 1 and that it is now desired to prepare a foundation in the selected location, the caisson is then flooded and as a result the caisson will settle from the position of FIG. 1 into the position of FIG. 2. Due to its own weight the caisson will penetrate to a certain extent into the silt at the bottom. The penetration due to weight may be deepened by providing an armored edge 15 on the caisson wall. It is also advisable to provide, as shown, a depending apron 12 to prevent washouts by water currents below the caisson. The apron may be made of sheet metal, sheet piles, etc. A driving or ramming shaft 16 indicated in dotted lines in FIG. 2 and more in detail in FIG. 2a is slipped over each pile 2. to be driven so that the shaft rests with its lower end upon the top of sealing collar 5, 6 and preferably protrudes slightly above the upper end of pile 2. In the first step of the driving operation, an axial force is applied to the driving shaft 16 whereby the collar and the pile are displaced jointly in the respective bore 7 or 8. To prevent a displacement of pile 2 in reference to the collar which would be undesirable at this stage of the driving operation, it is advisable to clamp shaft 16 to pile 2 by suitable clamping means 17 indicated in FIG.

2a. The clamping means as shown comprise clamping .jaws 17a which can be tightened or loosened by means of screw bolts 17b. The collar and the pile are driven jointly until the collar is lowered into the position shown in FIG. 3. The clamp means 17 are then loosened and the shaft from which it is discharged along the path 13 indicated in FIG. 5, and/ or through openings in the lower end of the pile shaft. The concrete will gradually fill the cavity so that the piles become encased in a jacket 10. The concrete will also be forced to penetrate to a certain extent into the surrounding soil strata, the more so as it is prevented from escaping upwardly due to the closure formed by collar 5, 6. Sleeve 4- serves to confine the concrete near the collar since at that level the soil is obviously very loose, thus counteracting a loss of concrete by dissipation into the surrounding soil. As is evident, a. strong anchoring of the piles can be obtained by using a high pressure feed for the concrete and even a certain stressing of the soil layers.

Finally the bores 7 and 8 are also filled with concrete.

The depth to which the piles are driven into the ground depends, of course, upon the depth at which solid loadcarrying ground is found and also upon the structure to be erected upon the foundation. If necessary, several lengths of piles can be joined as is indicated at 2a.

It has been found that after the caisson has been grounded and anchored as shown in FIG. 3, heavy and also high structures may be erected, including structures such as high masts, derricks, etc. which transmit high lateral forces upon the foundation for instance, due to wind, and the use of Winches.

It has further been found that a few weeks after completing the driving operation, the caisson can be stressed against the ground in which it is anchored, since the piles will transmit high tension forces to the ground. The filling of bores 7 and 8 with concrete is preferably eifected after the stressing of the caisson.

While the invention has been described in detail with respect to a certain now preferred example and embodiment of the invention it will be understood by those skilled in the art after understanding the invention, that various changes and modifications may be made without departing from the spirit and scope of the invention, and it is intended, therefore, to cover all such changes and modifications in the appended claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. A structure for grounding an underwater foundation, said structure comprising a floatable caisson having bores through its side walls parallel thereto and issuing in the bottom of the caisson, a plurality of hollow piles extending through said bores, the leading end of each pile protruding from the bottom of the caisson, an enlarged foot at the protruding end of each pile, an annular sealing collar slidably fitted in each of said bores at the bottom end thereof, each of said piles extending slidably through the respective collar, a driving sleeve retractably fitted in each bore coaxially with the pile portion in the respective bore, the leading end of each sleeve abutting against the respective collar, and releasable clamping means for releasably clamping together the pile and the sleeve, whereby upon tightening of the clamping means and application of a downwardly directed driving force upon the sleeve, said sleeve, jointly with the respective pile and the respective collar, is downwardly displaced, and upon release of the clamping means and application of a downwardly directed force upon the pile, said pile is downwardly displaced with reference to the respective collar.

2. A structure according to claim 1, wherein the bore portion receiving the collar is widened in cross-sectional area to form a shoulder within the bore, said collar abutting against the shoulder prior to downward displacement of the collar by means of the driving sleeve.

3. A structure according to claim 1, wherein said caisson has a top wall and a bottom wall, a central boss extending between said two walls and including bores extending lengthwise of the boss and issuing in the bottom wall of the caisson, one of said collars being fitted in each of the bores at the bottom end of the boss, and a pile extending slidably through each of said bores and having an enlarged pile foot protruding from the caisson.

4. A structure according to claim 1, wherein an apron depends from the side walls of the caisson, encompassing the peripheral outline thereof.

References Cited in the file of this patent UNITED STATES PATENTS Austria Oct. 10, 1957 

